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Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption, other

Remarks:

soil-adsorption-reference data

Type of information:

experimental study

Adequacy of study:

key study

Study period:

29 June 2017 - 07 November 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC))

Version / remarks:

2008

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))

Version / remarks:

2001

Deviations:

no

GLP compliance:

yes

Type of method:

HPLC estimation method

Media:

soil

Radiolabelling:

no

Test temperature:

35°C

Details on study design: HPLC method:

ANALITYCAL CONDITIONS
Instrument: Acquity UPLC system (Waters, Milford, MA, USA)
Detector: Acquity UPLC PDA detector (Waters)
Column: Acquity UPLC HSS Cyano, 100 mm x 2.1 mm i.d., dp = 1.8 µm (Waters)
Column temperature: 35°C +/- 1°C
Injection volume: 5 µL
Solvent A: methanol
Solvent B: water
Gradient:

Time Solvent A Solvent B
[minutes] [%] [%]
0 55 45
20 55 45
20.1 100 0
30 100 0
30.1 55 45
35 55 45

Flow: 0.4 mL/min
UV detection: 210 nm

Analytical monitoring:

no

Details on sampling:

Reference substance and test item solutions were injected in duplicate.
Blank solutions and the solution of the unretained compound were analyzed by single injection.

Details on test conditions:

PRINCIPLE OF THE TEST METHOD:
While passing through the column along with the mobile phase the test item interacts with the stationary phase. As a result of partitioning between mobile and stationary phases, the test item is retarded. The dual composition of a cyanopropyl stationary phase, having polar and non-polar sites allows for interaction of polar and non-polar groups of a molecule in a similar way as is the case for organic matter in soil or sewage sludge matrices. This enables the relationship between the retention time on the column and the Koc on organic matter to be established.

DETAILS ON MIBILE PHASE
The test item is a UVCB substance and consists of many compounds. Major part of the compounds does not have any ionisable group. Therefore the measurements were performed without buffering of the mobile phase (neutral pH).

CALIBRATION CURVE PREPARATION
Solutions of reference substances with known log Koc values based on soil adsorption data and the test item were analyzed. The capacity factor (k') of each compound was calculated from its retention time. The log k’ values of the references substances were plotted against the known log Koc values. A linear regression program was used to calculate the calibration curve. Linear regression analysis was performed using the least squares method. The coefficient of correlation (r) was calculated. The log Koc value for the test item was calculated by substituting its mean log k’ in the calibration curve. The value of log Koc obtained from duplicate measurements was within =/- 0.25 log units.
 

Key result

Type:

log Koc

Remarks:

highest value in the range (peaks 21 - 31)

Value:

> 5.63 dimensionless

pH:

7

Temp.:

35 °C

Remarks on result:

other: Detailed results on Log Koc and Koc are presented under HPLC results below.

Details on results (HPLC method):

The results of the HPLC method are given in Table below. The equation of the regression line was: log k’ = 0.319 x log Koc – 0.828 (r = 0.98, n = 16).

Substance Retention time (min) log Koc Koc
tr,1 tr,2 mean
Formamide 0.683 1 0.683
Acetanilide 0.897 0.899 0.898 1.26
Monuron 1.103 1.106 1.105 1.99
2,5-Dichloroaniline 1.256 1.261 1.259 2.55
Naftaleen 1.460 1.466 1.463 2.75
Benzoic acid phenylester 1.715 1.723 1.719 2.87
Fenthion 2.290 2.304 2.297 3.31
Phenantrene 2.536 2.549 2.543 4.09
4,4'-DDT 6.149 6.178 6.164 5.63
TI208171 peak 1 0.483 0.477 0.480 < 1.26 < 1.8 x 101
TI208171 peak 2 0.681 0.683 0.682 < 1.26 < 1.8 x 101
TI208171 peak 3 1.091 1.093 1.092 1.90 7.9 x 101
TI208171 peak 4 1.246 1.248 1.247 2.34 2.2 x 102
TI208171 peak 5 1.381 1.384 1.383 2.63 4.3 x 102
TI208171 peak 6 1.557 1.561 1.559 2.94 8.7 x 102
TI208171 peak 7 1.738 1.742 1.740 3.19 1.6 x 103
TI208171 peak 8 1.925 1.929 1.927 3.42 2.6 x 103
TI208171 peak 9 2.179 2.184 2.182 3.67 4.7 x 103
TI208171 peak 10 2.397 2.403 2.400 3.86 7.2 x 103
TI208171 peak 11 2.683 2.686 2.685 4.06 1.2 x 104
TI208171 peak 12 3.187 3.189 3.188 4.37 2.3 x 104
TI208171 peak 13 3.494 3.496 3.495 4.53 3.4 x 104
TI208171 peak 14 3.735 3.737 3.736 4.64 4.4 x 104
TI208171 peak 15 3.980 3.984 3.982 4.75 5.6 x 104
TI208171 peak 16 4.301 4.306 4.304 4.87 7.5 x 104
TI208171 peak 17 4.781 4.789 4.785 5.04 1.1 x 105
TI208171 peak 18 5.105 5.112 5.109 5.15 1.4 x 105
TI208171 peak 19 5.441 5.439 5.440 5.24 1.8 x 105
TI208171 peak 20 5.865 5.870 5.868 5.36 2.3 x 105
TI208171 peak 21 6.556 6.579 6.568 > 5.63 > 4.3 x 105
TI208171 peak 22 6.721 6.726 6.724 > 5.63 > 4.3 x 105
TI208171 peak 23 7.505 7.516 7.511 > 5.63 > 4.3 x 105
TI208171 peak 24 7.794 7.807 7.801 > 5.63 > 4.3 x 105
TI208171 peak 25 8.548 8.560 8.554 > 5.63 > 4.3 x 105
TI208171 peak 26 8.815 8.824 8.820 > 5.63 > 4.3 x 105
TI208171 peak 27 10.740 10.743 10.742 > 5.63 > 4.3 x 105
TI208171 peak 28 11.528 11.529 11.529 > 5.63 > 4.3 x 105
TI208171 peak 29 11.577 11.578 11.578 > 5.63 > 4.3 x 105
TI208171 peak 30 11.663 11.664 11.664 > 5.63 > 4.3 x 105
TI208171 peak 31 11.743 11.745 11.744 > 5.63 > 4.3 x 105
TI208171 peak 32 11.784 11.785 11.785 > 5.63 > 4.3 x 105
TI208171 peak 33 11.806 11.807 11.807 > 5.63 > 4.3 x 105
TI208171 peak 34 11.831 11.833 11.832 > 5.63 > 4.3 x 105

Adsorption and desorption constants:

The equation of the regression line was: log k’ = 0.319 x log Koc – 0.828 (r = 0.98, n = 16).

Transformation products:

not specified

Validity criteria fulfilled:

yes

Conclusions:

The soil adsorption of the test item was determined according to OECD Guideline No. 121, EC Guideline No. C.19 and GLP principles.
The HPLC method was applied, using soil-adsorption-reference data
The test item is a UVCB substance, with a complex composition. The components of the test item have Kocvalues in the range of < 1.8´101to > 4.3´105. It corresponds with log Kocvalues of < 1.26 to > 5.63.

Executive summary:

The soil adsorption of the test item was determined according to OECD Guideline No. 121, EC Guideline No. C.19 and GLP principles.

The HPLC method was applied, using soil-adsorption-reference data

The test item is a UVCB substance, with a complex composition. The components of the test item have K_ocvalues in the range of < 1.8´10¹to > 4.3´10⁵. It corresponds with log K_ocvalues of < 1.26 to > 5.63.

Description of key information

The Objective of the study was the determination of the soil adsorption of the test item according to OECD Guideline No. 121, EC Guideline No. C.19 and GLP principles.

The HPLC method was applied, using soil-adsorption-reference data

The test item is a UVCB substance, with a complex composition.The components of the test item have K_ocvalues in the range of < 1.8 x 10¹to > 4.3 x 10⁵. It corresponds with log K_ocvalues of < 1.26 to > 5.63.

The lowest Koc value that was reliably quantified (i.e. the response was within the calibration range), was Koc = 79. Therefore, this Koc value was used as a worst-case value to calculate PNECsediment and PNECsoil. However, the highest Koc value that was reliably quantified was Koc = 230000. The highest Koc is considered worst-case for calculation of PECs for sediment and soil, therefore this Koc value is used as key value for chemical safety assessment.

Key value for chemical safety assessment

Koc at 20 °C:

230 000

Additional information

[range measured: Koc 79 - 230000, LogKoc: 1.9 - 5.36]

[range of reference substances: Koc <18 - >430000, LogKoc <1.26 - >5.63]

[LogKoc: 5.36]